Mothers who catch a flu during pregnancy may increase the risk of their child developing schizophrenia

Mothers who catch a flu during pregnancy may increase the risk of their child developing schizophrenia later on in life.

Schizophrenia is a chronic, severe, and disabling brain disease. Approximately 1 percent of the population develops schizophrenia during their lifetime — more than 2 million Americans suffer from the illness in a given year.

Although available medications are reasonably effective in treating the positive symptoms of the illness such as hallucinations and delusions, recent research indicates that cognitive impairments in areas such as attention, memory and problem solving are responsible for much of the disability associated with the disease.

The research by the New York State Psychiatric Institute and the Mailman School of Public Health at Columbia University suggests that flu in the first half of pregnancy was linked to a three-fold increase in the risk of schizophrenia. Catching the flu in the second half of pregnancy appeared to have no ill effects.

The researchers estimate that 14% of schizophrenia cases may be linked to exposure to the flu virus in the womb. This research represents the strongest evidence so far that prenatal exposure to influenza plays a role in schizophrenia.

The findings are based on analysis of blood samples from 64 patients with schizophrenia and 125 subjects without the disease. samples were tested for antibodies to determine if flu exposure had occurred during pregnancy.

The children who seemed to be most at risk were those whose mothers contracted flu in the first 13 weeks of pregnancy.

Researcher Dr Ezra Susser said: "These findings represent the strongest evidence thus far that prenatal exposure to influenza plays a role in schizophrenia.

"The findings will need to be duplicated in other groups of people before we can draw firm conclusions from these results.

"At this time, we advise against using these results for any public health policy or individual preventive actions.

"However, if the results are confirmed in further studies, and the pathways are better understood, they could have very important implications for prevention."

Exactly why exposure to the flu virus in the womb should increase the risk of schizophrenia is unknown.

Data to date suggest that there is no single gene for schizophrenia. Instead there are multiple genes involved, each exerting a small to moderate effect on disease risk. These interact with environmental factors in the early stages of an individual's development to produce vulnerability to the illness.

The research is published in the current issue of the Archives of General Psychiatry.